The invention relates to apparatus for treating photosensitive materials with liquids, especially to improvements in developing machines for exposed photographic paper, exposed photographic films and the like. More particularly, the invention relates to improvements in developing and like apparatus of the type wherein the photosensitive materials are caused to orbit while being contacted by a liquid.
It is known to develop exposed photographic paper or exposed photographic films in a drum-shaped conveyor which is caused to rotate about a horizontal axis and repeatedly dips the photosensitive material into a developing, bleaching or fixing solution. As a rule, the supply of liquid is selected in such a way that the photosensitive material comes in contact with the liquid only during travel along the lower part of its endless path. The conveyor is a lattice- or grid-like structure which carries clamps or like retaining devices for photosensitive material. The retaining devices are designed and positioned to maintain the attached photosensitive material close to the periphery of the conveyor. When the latter is in use, its lower portion dips into a supply of liquid in a vessel and the conveyor is set in motion so that successive retaining devices advance the respective photosensitive materials into, through and out of the body of liquid during each revolution of the conveyor. When the treatment with a developing solution is completed, the conveyor is caused to dip into a supply of fixing solution, followed by a supply of bleaching medium, and so forth. Washing in water or in another cleansing fluid can follow the treatment with developing, fixing and bleaching media so that the developing solution is washed away before the thus treated photosensitive material is permitted to come into contact with the next solution, and so forth. The conveyor can be transferred from a preceding vessel into the next following vessel when a particular stage of development is completed. Alternatively, the apparatus employs a single vessel and the latter is evacuated after each stage of treatment so that it can receive the next liquid medium.
An advantage of such developing apparatus is that they can operate with relatively small quantities of liquids. This will be readily appreciated since only a single piece of photosensitive material or a very small number of pieces of photosensitive material will actually dip into the body of liquid in the adjacent vessel. However, presently known rotary developing apparatus also exhibit a number of drawbacks, especially as regards the mode of securing photosensitive material to the conveyor and the quality of the developed products. Thus, the developed material can exhibit streaks due to the establishment of currents in the body of liquid. Moreover, the individual items of photosensitive material cannot be placed too close to each other so that they would overlap during travel through a developing solution or another liquid. This reduces the output of the apparatus because the conveyor can carry only a limited number of sheets of exposed photographic paper, exposed photographic films and like photosensitive materials.
It is further known to simply dip exposed photosensitive materials (such as exposed photographic paper or exposed photographic films) into a body of liquid. The photosensitive material is placed into a basket or into a like container which is permeable to liquids, and the container is thereupon immersed into a body of liquid in a tank. This enhances the quality of development because the body of liquid in the tank is stagnant, i.e., it does not form currents which could cause streaking and like undesirable phenomena. However, such apparatus must employ large quantities of developing, fixing, bleaching and other solutions.